Musnad Abu Ya'la al-Mawsili 239:4

Muhammad ibn Qudamah narrated to us, Abu Bakr ibn Ayyash narrated to us, from Abu Yahya, from Mujahid, who said: A man passed by Ibn Abbas, and he said, "Indeed, this man loves me." They said, "And what makes you know that, O Abu Abbas?" He said, "Because I love him."